Synopsis:
The article is on pace 32, the article is 3 pages long, with diagrams of "Old Style" Paralever final drives, and EVO Paralevers. These are oilhead and K series motorcycles.
As to the number of occurances of this failure, statistics are difficult to gather as BMW will not talk about it on or off the record. These failures were insignificant prior to model year 2001. Fact: of 38 Palever BMWs that entered the 2007 Iron Butt Rally 14 were R1200 models, that is EVO Paralever bikes; four did not finish due to final drive failures, a 29% failure rate. (Side note: others have indicated these bikes were carrying heavier than normal loads, not cited in the MCN article). EVO paralevers are 2004 and later models with the hollow rear axle and 50 mm hole.
A symptom cited in the article was oil leakage around the final drive seals eventually spreading to the rear wheel; others include metal particles on the magnetic drain plug (it was suggested one be fitted if not present).
There is an extensive technical discussion of failure modes, preload pressures, pinion gear's needle bearing, final drive lubricant change frequency, viscosity of the fluid. The article notes these are only theories as the BMW technicians who have examined cases of this occurance are silent.
Preventative measures: check final drive axle bearing play when bike is on centerstand by rocking the wheel at 4 opposed points. Any play indicates inspection by a mechanic (BMW technician) is in order. Also, draining of the final drive fluid and inspection for any metal particles indicates further inspection by a mechanic (BMW technician) is in order.
The article noted none of these failures has been the cause of a crash.
A website, http://www.bmwfinaldrive.com, was cited and is maintained by a BMW owner; 80 people have reported failures.
Reading of this article is highly recommended; the above is only a brief synopsis.
